The present invention relates to the field of variable displacement bent axis hydraulic units. Bent axis hydraulic units have been known for many years.
Such devices obviously have power output limited to their physical size. When additional power is required, a solution is to provide a unit of larger size. However, space and size become a problem in certain vehicle designs and serve to prevent larger bent axis hydraulic units from accommodating this situation when more power and limited space are specified.
Prior art shows attempts to use hydromodules that have multiple yokes; however, these inventions fallen short when attempting to provide a hydromodule with bent axis hydrostatic units that have a simplified construction with as few parts as necessary, as well as a compact construction with the yokes taking up as little space as possible. For example, the U.S. Pat. No. 6,530,855 patent to Folsom discloses bent axis hydrostatic modules that have multiple yokes. When referring to WO99/24738 as referred to by Folsom, one can see Folsom relies on a stationary manifold block to accommodate its fluid passages between the pump and the motor, with the porting of hydrostatic flow through the piston slippers to the cylinder block. Thus, the Folsom patent shows a sizeable construction with a large number of separate parts which potentially results in a higher unit manufacturing cost as well as potential decreases in the unit's reliability.
It is therefore a principal object of this invention to provide a bent axis hydrostatic unit with a pair of bent axis hydrostatic power units working in unison in side by side relation to provide a greater power output, and which includes parallel, unidirectional rotatable power shafts; dual swingable yokes pivotally mounted on a frame, and means for independently pivoting the yokes about parallel axes.
It is a further object of the invention to provide a bent axis hydrostatic module with multiple yokes wherein the yokes are of single piece construction.
It is another object of the invention to provide a bent axis hydrostatic module with multiple yokes wherein the yokes contain integrated fluid passages.
These and other objects, features, or advantages of the present invention will become apparent from the specification and claims.